High Frame Rate Ultrasonic Imaging Research Articles

High Frame Rate Ultrasonic Imaging for Measurement of Tissue Dynamics

High Frame Rate Ultrasonic Imaging for Measurement of Tissue Dynamics

Study on the transmission system of high frame rate ultrasonic imaging based on the non-diffraction wave

Array beam field is a necessary condition for high frame rate(HFR) ultrasonic imaging system according to the non-diffraction wave theory. However, the sine function characteristic of array beam waves makes it more difficult to weight the ultrasonic wave transmission signal so the transmission system is very complex. To solve this problem, this paper proposes an effective solution. Based on Fourier transform theory, the energy component of the square wave focuses mainly on the fundamental wave. In this paper a kind of square wave with a single value is utilized to weight the transmitted signals from an ultrasonic transducer. Thus only one power signal source and a very simple electronic switch system can be used to achieve this kind of transmission circuit in the HFR system. Experiments show that such an option has little impact on the image quality of the HFR, however it greatly simplifies the HFR ultrasound imaging system.

Ultrafast imaging of the arterial pulse wave

We propose a novel technique for measuring directly in real time, locally and non-invasively the pulse wave velocity (PWV) on peripheral arteries. Very high frame rate ultrasonic imaging (> 1000 frames/s) was achieved for tracking in 2D the propagation of transient vibrations along arterial wall. The arterial pulse waves are observed within a single cardiac cycle allowing the estimation of the pulse wave velocity with a good accuracy. In this study, this technique was validated for PWV evaluation on 25 healthy patients using conventional sonographic probes. The mean carotid PWV was found to be 5.5 ± 1.2 m/s (from 4.5 m/s to 7 m/s) with good intra and interobserver variability (inferior of 10% of the mean). These data suggest a good accuracy and reproducibility of the technique for real time PWV evaluation in vitro and on healthy volunteers.

High frame rate ultrasonic imaging through Fourier transform using an arbitrary known transmission field

The high frame rate (HFR) method, derived from the limited diffraction beams [Jian-yu Lu. 2D and 3D high frame rate imaging with limited diffraction beams. IEEE Trans Ultrason Ferroelectrics Freq Control 1997;44(4):839–56; Jian-yu Lu. Experimental study of high frame rate imaging with limited diffraction beams. IEEE Trans Ultrason Ferroelectrics Freq Control 1998;45(1):84–97; Hu Peng, Jianyu Lu, XueMei Han. High frame rate ultrasonic imaging system based on the angular spectrum principle. Ultrason 2006;44(Suppl):e97–9] theory, has a drawback that its imaging area, as wide as its array beam transmission field, can generally not be wider than the transducer is long; and that the only way to widen the area is to steer the transmission beams several times from different angles, which lowers the frame rate. Besides, the array beam field is quite demanding to produce. To widen the imaged area, we developed an extended, more general HFR method for 2D imaging. It allows any form of transmission field as long as the field is known, and it achieves the frame per transmission imaging rate. For verification, computer simulations use a linear transducer array and a cylindrical diffraction transmission field defined by the zero order Hankle function. The output images are in the sector format and have low sidelobes. The simulation results are consistent with our theory.

Study on application of complementary Golay code into high frame rate ultrasonic imaging system

The high frame rate (HFR) ultrasonic imaging system, which is developed with limited diffraction beams, constructs images at a high frame rate. However the rectangular imaging area, to some extent, restricts the far field imaging information. At the same time, by virtue of one transmission event for constructing image, the system suffers from low SNR. In this paper we present a computationally efficient method to construct sector mode image and to increase the SNR in HFR system. The method uses orthogonal complementary Golay coded excitation to realize two transmit and receive events. Each emission simultaneously transmits two plane waves with different transmission angle. Then according to Golay code orthogonality, the received echo signals related to different angles are isolated and used to construct two images of different imaging area by HFR method. Finally the two images are synthesized to one frame of sector mode image.

High frame rate ultrasonic imaging system based on the angular spectrum principle

A kind of high frame rate (HFR) 2D and 3D imaging method was developed by Jianyu Lu in 1997. Because only one transmission is required to construct a frame of image, this method can reach an ultra high frame rate (about 3750 volumes or frames per second for biological soft tissues at a depth of 200 mm). In this paper, a new HFR method is presented in the view of angular spectrum. Compared with conventional dynamic focusing method which uses delay-and-sum processing, and Lu’s HFR method which uses a kind of special weighting on the received signal, the new method only uses the Fourier transform algorithm to construct image. So the system implementation of the method could be greatly simplified. During constructing image, several array beams with different parameter are used as transmitted signal, and the spectrum of a frame of image is obtained by synthesizing the image spectrums related to different transmit event. The simulation result shows that the solution not only suppresses the sidelobe of system greatly and obtains the high quality image, but also still keeps high frame rate to some extent.

Increasing field of view of high frame rate ultrasonic imaging

A high frame rate imaging method has been developed recently based on the theory of limited diffraction beams for medical diagnosis. This method constructs images in a direction normal to the transducer surface. In this report, the high frame rate method is extended so that it will not only construct images in the normal direction, but also in any oblique directions. This increases the image construction area because images from several oblique angles can be combined. A new equation has been derived for this extension. A computer simulation was performed. Results show that the field of view of images constructed with the extended method is increased from about 15.74 deg to about 96.57 deg with a linear array of a width (foot print) of about 18.288 mm after combining images from only seven angles (the depth of the images is assumed to be 66.12 mm). This work is significant because a large field of view with a small transducer footprint is desirable for high frame rate heart imaging. [Work supported in part by Grant No. HL60301 from NIH.]